Three environmental groups filed a federal lawsuit on Tuesday alleging that the U.S. Fish & Wildlife Service has not done enough to protect the lesser prairie chickens.

The Fish & Wildlife Service listed the birds, which are native to Kansas and neighboring states, as a threatened species, which is a step below endangered.

Kansas officials have said this move goes too far and will result in regulations that will hurt the state’s economy. But conservationists contend the threatened listing doesn’t go far enough to protect the birds.

Species that are designated as threatened receive some protections, but the Fish & Wildlife Service invoked an exemption in the Endangered Species Act to allow Kansas and other states to proceed with an already formed conservation plan without new regulations.

The lesser prairie chicken population declined to 17,616 last year, a 50 percent drop from the previous year. Kansas, Colorado, New Mexico, Oklahoma and Texas have agreed to a plan that would provide 3.6 million acres to go toward conservation between the five states.

Conservationists say the plan fails to offer adequate protections against further population decline and that the threatened designation lacks the teeth to enforce protections that would be available if the bird were placed on the endangered list.

“Habitat destruction and drought are continuing to devastate the small remaining population of this magnificent grassland bird,” said Jay Lininger, a senior scientist with the Center for Biological Diversity, one of the organizations. “These unenforceable pro-industry agreements fail to ensure the level of protection required by the Endangered Species Act to avert extinction.”

“This iconic grassland bird deserves more than a hollow promise of protection,” said Jason Rylander, senior attorney with Defenders of Wildlife. “These agreements are far from foolproof and even the Service admits that they don’t know for certain how the agreements will impact the prairie-chicken.”

Gov. Sam Brownback did not mince words when responding to the news of the conservationists' suit.

“It is not surprising that these extremist environmental organizations would file a lawsuit in Washington, D.C. that effectively attempts to shut down the energy and agriculture economies of western Kansas,” Brownback said in a statement.

“Their previous litigation is what caused the threatened listing of the Lesser Prairie Chicken in the first place. But it appears they are not satisfied with the multi-million dollar costs already imposed on Kansans – what they really seek is a level of economic devastation that would do nothing to enhance the species or its habitat,” he said. “It is the Governor’s job to protect the rights of Kansans and that is what I am doing. We will oppose this position and move forward with our own initiatives to reverse the unwarranted federal action.”

Kansas has joined Oklahoma in a federal lawsuit against the designation.

The Legislature also passed a bill, signed into law by Brownback, that declared state sovereignty over the birds to block any enforcement of federal regulation.

If the lawsuits, which are being litigated in different federal circuits, result in conflicting rulings then it is possible that the prairie chicken issue could be argued in front of the U.S. Supreme Court one day.